320-28X bearing: complete specifications & equivalents
The 320-28X is a ISO 355 radial bearing sized 28 x 52 x 16 mm (bore x OD x width). Verify dimensions against the official catalog before ordering.
Specification table
| Parameter | Value |
|---|---|
| Brand | NTN |
| Bore diameter d | 28 mm |
| Outer diameter D | 52 mm |
| Width B | 16 mm |
| Material | GCr15 |
| Seal / shield | open |
| Internal clearance | CN |
| Tolerance class | P0 |
| Cage | steel |
| Basic dynamic load rating C | 37 kN |
| Basic static load rating C0 | 40.5 kN |
| Limiting speed (mechanical) | 7300 rpm |
| Operating temperature | -40 to +120 °C |
| Mass | 146 g |
| Manufacturer designation | NTN 320/28X |
| Standard | ISO 355 |
| Catalog version | NTN Ball and Roller Bearings CAT.No.2203E |
| Last verified | 2026-10-01 |
Source: catalog reference (NTN Ball and Roller Bearings CAT.No.2203E) · extracted 2026-10-01
Parameters extracted from the official NTN Ball and Roller Bearings catalogue (NTN Ball and Roller Bearings CAT.No.2203E); NTN® is a trademark of NTN Corporation, used here for identification only — mpnbase is not an authorized NTN distributor. Boundary dimensions are ISO 15 interchangeable; current production values may differ, verify at ntnglobal.com.
Dimensions in inches & 32000-series range
| Bore d | 1.102 in |
|---|---|
| Outer diameter D | 2.047 in |
| Width B | 0.63 in |
| ISO bore code | 20 |
| Radial section height (D−d)/2 | 12 mm |
| Smallest bore in 32000-series | 20 mm |
| Largest outer diameter in 32000-series | 650 mm |
| Width range across 32000-series | 15–130 mm |
| Bore position in 32000-series (smallest first) | 4 of 43 |
| Bore above smallest 32000-series size | 8 mm |
Cross references & equivalents
| Equivalent model | Brand | Match level | Note |
|---|---|---|---|
| 320-22 | SKF | verify Commonly quoted cross reference; confirm against the target catalog before ordering. | Model-number interchange per ISO 15; confirm dimensions, sealing and ratings in the supplier catalogue. |
| 320-28 | SKF | full Dimensions and internal design equivalent — standard interchange. | Identical ISO 15 envelope, seal and ratings band — standard interchange; re-verify precision class and clearance per supplier. |
| 320-32 | SKF | verify Commonly quoted cross reference; confirm against the target catalog before ordering. | Model-number interchange per ISO 15; confirm dimensions, sealing and ratings in the supplier catalogue. |
Interchange levels: full standard interchange · partial verify parameters · verify manual confirmation required. Links resolve to the equivalent model's specification page where available.
How the 320-28X model number is decoded
320/28X is the NTN 4T catalogue entry for a 28×52×16 mm metric tapered roller bearing — separable cone and cup, designed for combined radial and axial load as an individually adjusted bearing. Digit by digit, the bare number identifies the low-section 32000 family tuned for low friction and a bore code resolving to 28 mm; 52 mm OD and 16 mm assembled T are the matching ISO 355 boundary dimensions shared with other makers of the same dimension series. NTN adjusts these bearings by cup or cone position rather than shipping a preloaded set; the mounting drawing must state end play or preload for 320/28X, since running clearance is set during assembly. The two speed columns differ by a factor of .75 (grease/limiting 7,300 vs oil 9,700 r/min); heat generation at the cone rib decides which lubrication a real 320/28X arrangement can sustain. Fillet radii must clear the ring chamfers of the 52 mm cup and 28 mm cone; use undercut shoulders so the rings seat fully rather than bridging on a shaft radius.
Typical equipment & failure modes
Common applications
- construction-equipment wheel and pivot hubs
- truck and bus wheel hubs in paired arrangements
- industrial gearbox and speed-reducer shafts
- bevel and helical pinion drives with high thrust component
Known failure patterns
- cone-raceway spalling at the large rib when preload is set too high for the lubricant film
- smearing on the roller large ends and cone rib after a dry start with preload but no oil film
- flaking on one cone only when a back-to-back / face-to-face pair is loaded unevenly by a bent shaft
- cage damage from a mounting blow delivered through the roller complement instead of the ring face
- false brinelling on a stationary paired set exposed to external vibration
Selection pitfalls — read before you substitute
- Hub and pinion bearings of this 28 mm bore class are commonly adjusted in pairs; verify end play against the axle drawing and re-torque after bedding-in rather than trusting the initial preload on 320/28X.
- The thin 16 mm section of 320/28X is built for low friction and tight envelopes, not the heavy preload of a 322/323 set; over-tightening adjustment on this 28 mm bore smears the roller ends against the rib.
- Open 320/28X units have no seals: a wheel-hub or gearbox application needs external sealing or the 7,300 r/min grease figure is meaningless once water reaches the cone rib.
- ISO 355 makes the 28×52 mm envelope interchangeable but not the ratings: NTN prints 37/40.5 kN for this execution, and a cheaper same-number part can differ in roller complement and steel.
- On slash-size and T-code bearings confirm the full code on both cone and cup before fitting: the 28 mm bore alone does not identify the cup, and a mismatched cone/cup set has no catalogue rating.
- The 37/40.5 kN ratings here are NTN Ball and Roller Bearings CAT.No.2203E figures for 320/28X (ISO 355 4CC); internal geometry legitimately differs between manufacturers, so re-verify ratings, adjustment and suffix before substituting another make on a rated drive.
Frequently asked questions
What are the dimensions and catalogue ratings of NTN 320/28X?
320/28X is a metric 4T tapered roller bearing to ISO 355: 28 mm bore, 52 mm outside diameter and 16 mm assembled width T (1.102 × 2.047 × 0.63 in). From NTN Ball and Roller Bearings CAT.No.2203E: C 37 kN, C0 40.5 kN (2203E prints no Pu for this size), grease limiting speed 7,300 r/min, oil speed 9,700 r/min, mass about 146 g. It is an open, separable cone/cup bearing with a pressed-steel cage.
What does the 4T prefix mean on 320/28X?
4T is NTN's tapered roller bearing brand mark, stamped on the cone and cup in the factory. It identifies the NTN 4T programme and is not a dimension, so the catalogue and this page list the bare ISO 355 number (320/28X); the lower-case 4t- factory spelling of the code is retained among the search aliases.
How does the 320/28X designation encode the 28 mm bore and what is 4CC?
28 mm bore is printed directly after the slash in the slash-size convention. The 52 mm OD and 16 mm assembled T follow the ISO 355 dimension-series plan. 4CC is the maker-neutral ISO 355 abbreviation for this dimension series (the same code other manufacturers print); 4T is NTN's own brand mark.
Why does 320/28X list two speeds, 7,300 and 9,700 r/min?
The lower figure, 7,300 r/min, is the grease-lubricated limiting speed — the mechanical ceiling for the cage, rollers and cone-rib contact. With oil lubrication NTN rates 320/28X at 9,700 r/min because oil removes rib-contact heat better. Real limits still depend on preload, oil flow and cooling.
What does the suffix on 320/28X mean?
Suffix reading on 320/28X: X marks the execution built to the ISO boundary-dimension section (interchangeable envelope, NTN internal geometry); the suffix is part of the order number and the variants are not interchangeable articles.
Reviewed & verified by the MPN Base engineering desk against source catalog NTN Ball and Roller Bearings CAT.No.2203E on 2026-10-01. Read our editorial & correction policy.